Adaptive disk power management for portable media players

To support the large storage requirements, consumer electronics for video playback are increasingly being equipped with hard disk drives (HDD) that consume a significant amount of energy. A video player may prefetch many frames to give disk an opportunity to go to standby mode, but this may cause playback to be distorted or stopped if timely power mode transitions are not incorporated. We present the design, implementation and evaluation of a data prefetching scheme for energy-aware video data retrieval for portable media players (PMP). We formulate the problem when the prefetching is used for variable-bit-rate (VBR) streams to reduce disk energy consumption and then propose a new energy-aware data retrieval scheme that prefetches video data in a just-in-time way so as to increase the period in which disk stays in standby mode while guaranteeing the real-time service. We implemented our scheme in the legacy video player called Mplayer that is typically used for Linux-based consumer devices. Experimental results show that it saves energy as much as 51% compared with conventional schemes.